A major
drawback of conventional photocatalysts like TiO<sub>2</sub> is the
limit of only working under ultraviolet irradiation. As a
solution, visible-light-driven photocatalysts have been explored in
recent years but full-sunlight-driven photocatalysts are still lacking.
Herein, multielement-codoped (Mn, Fe, Si, Al, S, F, etc.) TiO<sub>2</sub> nanomaterials were prepared from an industrial high-Ti cinder
(HiTi) by a two-step hydrothermal method using NaOH and NH<sub>4</sub>F (or H<sub>2</sub>O) as morphology controlling agents. The prepared
HiTi photocatalyst exhibits a strong absorption at near full-sunlight
spectrum (300–800 nm). Among all TiO<sub>2</sub>-based photocatalysts
without any noble metal cocatalyst, the photocatalytic H<sub>2</sub> evolution rate on NaOH- and H<sub>2</sub>O-hydrothermally treated
HiTi (HiTi-TiO<sub>2</sub>) is remarkably superior to the reference
P25 TiO<sub>2</sub> powders by a factor of 3.8 and thus is the highest.
However, NaOH- and NH<sub>4</sub>F-treated HiTi (HiTi-TiO<sub>2</sub>-F) shows a lower photoreactivity than HiTi-TiO<sub>2</sub> does.
Mechanistic studies show that the multielement-doped TiO<sub>2</sub> can synergistically harvest full span sunlight to greatly increase
light absorption, while suppressing the charge recombination and reducing
the reaction barriers for efficient water splitting. Importantly,
the amount of produced industrial cinder is huge in China, and it
is dumped on the ground in very large mounds, which results in serious
pollution. This study may open a promising recycling approach to treat
the waste for sustainable energy use
